<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    *{
        padding: 0;
        margin: 0;
        box-sizing: border-box;
    }

    html{
        font-size: 100px;
    }

    body{
        font-size: 16px;
    }

    #app{
        width: 4rem;
        margin: 0 auto;
        border: 1px solid black;
        height: 100px;
        display: flex;
        align-items: center;
    }

    .item{
        flex: 1;
        height: 100%;
        border: 1px solid blue ;
        display: flex;
        align-items: center;
    }
</style>
<body>
<div id='app'>
  <div class="item">
    <span class="green"></span>
  </div>
  <div class="item">
    <span class="yellow"></span>
  </div>
  <div class="item">
    <span class="red"></span>
  </div>
  <div class="item">
    <span class="count">30</span>
</div>
</div>
</body>
</html>